Preclinical evaluation of high-dose Griffithsin carrageenan fast-dissolving insert for HIV, HSV-2, and HPV prevention

Griffithsin (GRFT) is an antiviral lectin that blocks human immunodeficiency virus (HIV) entry. When combined with carrageenan (CG), GRFT has strong activity against herpes simplex virus type 2 (HSV-2) and human papillomavirus (HPV). We conducted a preclinical evaluation of a high-dose vaginal fast-dissolving insert (FDI) containing 3 mg GRFT-equivalent to 3× the clinical dose-and compared it with a 1 mg formulation. Studies included FDI disintegration (macaques, rabbits); GRFT pharmacokinetics, pharmacodynamics, and inflammatory response (macaques); toxicity (rats); and immunogenicity (macaques, rats). Disintegration times varied between species, emphasizing the importance of evaluating this parameter in humans. In macaques, cervico-vaginal lavage (CVL) GRFT concentrations exceeded levels associated with in vivo efficacy 12 h after administration of the 3 mg GRFT/CG FDI. Potent anti-HIV1_BaL activity was detected in CVLs collected 24 h following the 3 mg dose and 12 h after the 1 mg dose. CVLs inhibited HSV-2 at 4 h and HPV at 12 h after both GRFT doses. GRFT/CG FDIs caused no inflammatory response and did not alter vaginal pH. In rats, repeated daily dosing at up to 10× the clinical dose revealed no safety concerns. Although anti-drug antibodies (ADAs) developed in macaques and rats, systemic GRFT was undetectable, suggesting that ADAs are unlikely to alter pharmacokinetics. Overall, the CVL GRFT concentrations and anti-HIV activity following administration of 3 mg GRFT/CG FDIs suggest a longer protection window-at least 12 h-against HIV-1 compared with the 1 mg FDI, and both formulations demonstrate activity against HSV-2 and HPV. These findings support continued GRFT/CG FDI development.IMPORTANCEThere is an undeniable need to develop multipurpose prevention products that simultaneously protect against human immunodeficiency virus (HIV) and other sexually transmitted pathogens. To that end, we conducted a preclinical evaluation of a carrageenan-based fast-dissolving vaginal insert containing 3 mg of anti-viral lectin Griffithsin-equivalent to 3× clinical dose-and compared it with a 1 mg insert. Both formulations were safe and demonstrated potent anti-HIV, herpes simplex virus type 2 (HSV-2), and human papillomavirus (HPV) activity. Our data suggest that a 3× clinical dose Griffithsin formulation may afford an extended window of protection against HIV compared to the 1× dose formulation. These data support further development and clinical testing of high-dose Griffithsin carrageenan fast-dissolving vaginal insert.